"Klebsiella pneumoniae is considered intrinsically resistant to ampicillin because of the chromosomal blaSHV β-lactamase. However, amoxicillin-susceptible isolates have been sporadically reported. This retrospective observational study analyzes amoxicillin-susceptible K. pneumoniae isolates collected between 2016 and 2023 at a university hospital in France. Whole-genome sequencing, phylogenetic analysis, and virulence and resistance profiling were performed, and clinical data were reviewed. The study aims to characterize the genomic mechanisms underlying amoxicillin susceptibility and to assess associations with specific lineages, particularly hypervirulent clonal complex 66 (CC66), and clinical features."